president obama was in henderson, nevada, getting ready. last night he tried to lower expectations for himself at a rally in las vegas. >> i know folks in the media are speculating already on who is going to have the best zingers. >> you are! i don't know about that. who is going to put the the most points on the board. >> you are! no, no, governor romney is a good debater. i'm just okay. >> woodruff: by contrast a prominent romney supporting was out hyping his candidate's debating skills. new jersey governor chris christie on cbs's face the nation yesterday. >> i've seen mitt romney do this before. he's going to come in wednesday night and lay out his vision for america. he's going to contrast what his view is and what the president's record is. and the president's view for the future. this whole race is going to be turned upsidedown come thursday morning. >> woodruff: like wise president obama's senior advisor david pluf offerd this assessment on nbc's meet the press. >> challengers tend to benefit from debates. we've expected all along t